Optimization of liposomal topotecan for use in treating neuroblastoma

The purpose of this work was to develop an optimized liposomal formulation of topotecan for use in the treatment of patients with neuroblastoma. Drug exposure time studies were used to determine that topotecan (Hycamtin) exhibited great cytotoxic activity against SK-N-SH, IMR-32 and LAN-1 neuroblastoma human cell lines. Sphingomyelin (SM)/cholesterol (Chol) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)/Chol liposomes were prepared using extrusion methods and then loaded with topotecan by pH gradient and copper-drug complexation. In vitro studies showed that SM/Chol liposomes retained topotecan significantly better than DSPC/Chol liposomes. Decreasing the drug-to-lipid ratio engendered significant increases in drug retention. Dose-range finding studies on NRG mice indicated that an optimized SM/Chol liposomal formulation of topotecan prepared with a final drug-to-lipid ratio of 0.025 (mol: mol) was better tolerated than the previously described DSPC/Chol topotecan formulation. Pharmacokinetic studies showed that the optimized SM/Chol liposomal topotecan exhibited a 10-fold increase in plasma half-life and a 1000-fold increase in AUC0-24 h when compared with Hycamtin administered at equivalent doses (5 mg/kg). In contrast to the great extension in exposure time, SM/Chol liposomal topotecan increased the life span of mice with established LAN-1 neuroblastoma tumors only modestly in a subcutaneous and systemic model. The extension in exposure time may still not be sufficient and the formulation may require further optimization. In the future, liposomal topotecan will be assessed in combination with high-dose radiotherapy such as 131 I-metaiodobenzylguanidine, and immunotherapy treatment modalities currently used in neuroblastoma therapy

La resolució de situacions problemátiques a través de la lógica i calcul mental. 'La resolución de situaciones problemáticas a través de la lógica y el cálculo mental'

Conseguir una mejora de los resultados en el cálculo mental a través de un trabajo estructurado de este proceso de aprendizaje del niño de Párvulos y ciclo inicial, llevado a cabo manipulativa y experimentalmente. 90 alumnos elegidos aleatoriamente de una población de 270 sujetos pertenecientes a la escuela pública Sant Salvador de Tarragona de la muestra, 30 sujetos cursan segundo de Párvulos, 30 cursan primero de EGB y 30 cursan segundo de EGB. Elaboración de una programación exhaustiva y rigurosa de los objetivos de las Matemáticas en Parvulario y ciclo inicial, junto con una relación de actividades, material y tipología de problemas relacionados. Confección de dos pruebas, aplicadas oralmente, de problemas concretos a resolver, basados en una serie de esquemas básicos de situaciones problemáticas. Pasación de la prueba inicial a la muestra. Aplicación de la metodología propuesta que va, gradualmente, de la ayuda mediante manipulación y experimentación de material en la resolución de problemas hasta la utilización sólo de la representación mental. Pasación de la prueba final. Análisis de datos obtenidos y comparación de resultados. Dos pruebas orales 'ad hoc'. Material de experimentación diverso, estructurado y no estructurado. Distribuciones de frecuencias y porcentajes. Las líneas metodológicas propuestas han servido para agilizar en los niños el análisis de las situaciones problemáticas y al mismo tiempo agilizarles el cálculo mental. Las disposiciones de las situaciones problemáticas de los esquemas básicos pueden servir como base para la elaboración de un programa de ordenador que genere multiplicidad de situaciones problemáticas diversas automáticamente.CataluñaES

Dianthin-30 or gelonin versus monomethyl auristatin E, each configured with an anti-calcitonin receptor antibody, are differentially potent in vitro in high-grade glioma cell lines derived from glioblastoma

We have reported that calcitonin receptor (CTR) is widely expressed in biopsies from the lethal brain tumour glioblastoma by malignant glioma and brain tumour-initiating cells (glioma stem cells) using anti-human CTR antibodies. A monoclonal antibody against an epitope within the extracellular domain of CTR was raised (mAb2C4) and chemically conjugated to either plant ribosome-inactivating proteins (RIPs) dianthin-30 or gelonin, or the drug monomethyl auristatin E (MMAE), and purified. In the high-grade glioma cell line (HGG, representing glioma stem cells) SB2b, in the presence of the triterpene glycoside SO1861, the EC50 for mAb2C4:dianthin was 10.0 pM and for mAb2C4:MMAE [antibody drug conjugate (ADC)] 2.5 nM, 250-fold less potent. With the cell line U87MG, in the presence of SO1861, the EC50 for mAb2C4:dianthin was 20 pM, mAb2C4:gelonin, 20 pM, compared to the ADC (6.3 nM), which is >300 less potent. Several other HGG cell lines that express CTR were tested and the efficacies of mAb2C4:RIP (dianthin or gelonin) were similar. Co-administration of the enhancer SO1861 purified from plants enhances lysosomal escape. Enhancement with SO1861 increased potency of the immunotoxin (>3 log values) compared to the ADC (1 log). The uptake of antibody was demonstrated with the fluorescent conjugate mAb2C4:Alexa Fluor 568, and the release of dianthin-30:Alexa Fluor488 into the cytosol following addition of SO1861 supports our model. These data demonstrate that the immunotoxins are highly potent and that CTR is an effective target expressed by a large proportion of HGG cell lines representative of glioma stem cells and isolated from individual patients